This invention relates to outlets used to discharge lading from covered hopper railway cars, and, more particularly, to a gravity outlet which meets current American Association of Railways (AAR) regulations.
As is well-known, gravity outlets have been used on covered hopper railway cars for discharging ladings such as grains from the cars. See, for example, U.S. Pat. Nos. 4,599,948, 4,528,913, 4,214,536, 3,877,392, and 3,779,172, and United States patent application 08/052,135, all of which are assigned to the same assignee as the present invention, together with U.S. Pat. Nos. 4,534,298, 4,301,741, 3,938,861, 3,415,204, and 3,138,117. With respect to gravity outlets, there are a number of problem areas which exist. Among these are current outlet designs with which there is the possibility of contamination of one lading with another, adequate sealing of the outlet to prevent dirt, dust, debris, and moisture from migrating into the outlet and contaminating or spoiling the lading, the ease of use of current gate operating mechanisms, and the force required to open an outlet gate at the start of an off-loading operation.
With respect to the first of these concerns, current gravity outlets have standard size discharge openings; 13".times.42" (33.0 cm..times.106.7 cm.) being an exemplary standard size opening. However, it is not uncommon that within the outlet there are rectangularly shaped sections whose measurements differ from these. There may, for example be a segment whose length and/or width is slightly larger or smaller than the above. As a result, a shelf is created at the interface between the two outlet segments where lading can collect. If the outlet is not properly cleaned between ladings, particles of the previous lading will remain on the shelf and can contaminate a subsequent lading. Besides contamination, the particles may also cause spoilage of the subsequent lading. And, if the lading builds up and hardens on the outlet gate, it can prevent the outlet from properly closing. The outlet, because it is on the underside of the car, is exposed to all sorts of possible contaminants as the car moves from one location to another. Dirt, dust, collected moisture, and other kinds of debris are all thrown up around the outlet. Rainwater flowing down the sides of the car or sprayed up off the roadbed also can strike the outlet. Adequate sealing is required to prevent these contaminants from getting into the outlet and damaging the lading. In a different regard, when the outlet gate for the outlet is closed, lading sits atop the gate. When the gate is opened, it is withdrawn from the outlet. It is possible that the gate will carry particles of the lading away as it is moved. Not only does means that a small portion of the lading may be retained within the car, but also that this is yet anothere source of contamination and spoilage.
Typically, the outlet gate for a gravity oulet has a locking mechanism by which the gate is locked in its closed position so as to not inadvertently open during transit. When it is time to unload the car, opening the gate has heretofore been a two step operation. The first step is in unlocking the gate; the second, actually opening thegate. Because each covered hopper railway car has a number of hoppers in each unit, each hopper having its associated outlet, and a train typically includes many cars, the task of unlocking and then opening each separate outlet as each car is unloaded becomes a very time consuming task. Especially, when each gate has to be closed and then relocked after the hopper is empty. In addition, considerable amounts of torque often have to be applied to open a gate because of the "footprint" i.e. surface area of the gate upon which lading sits.
Recently, the AAR and grain elevator operators have addressed these various issues. One result has been promulgation by the AAR of new regulations concerning gravity outlet design and operation. This is AAR standard S-233. Among the requirements of this new standard are section 2.5 which requires the bottom outlet area of hoppers be designed, installed, and maintained to prevent entrance of water, waste, and debris during transit. Section 2.6 requires that the opening mechanism have a stipulated maximum breakaway torque under defined test conditions. For the 13".times.42" outlet mentioned above, the torque value is 700 ft.-lbs. Section 2.7 requires that for grain service there be a clear opening (no ledges, etc.) of the discharge gates. Section 2.8 stipulates that the locking mechanism be accessible from both sides of the railcar, and section 2.9 this mechanism be integrated with the gate operating mechanism. Finally, for purposes of this discussion, section 2.10 requires the gate mechanism to have an automatic locking mechanism.